title: Determination of molecular vibrational state energies using the ab initio semiclassical initial value representation: application to formaldehyde.
abstract: We have demonstrated the use of ab initio molecular dynamics (AIMD) trajectories to compute the vibrational energy levels of molecular systems in the context of the semiclassical initial value representation (SC-IVR). A relatively low level of electronic structure theory (HF/3-21G) was used in this proof-of-principle study. Formaldehyde was used as a test case for the determination of accurate excited vibrational states. The AIMD-SC-IVR vibrational energies have been compared to those from curvilinear and rectilinear vibrational self-consistent field/vibrational configuration interaction with perturbation selected interactions-second-order perturbation theory (VSCF/VCIPSI-PT2) and correlation-corrected vibrational self-consistent field (cc-VSCF) methods. The survival amplitudes were obtained from selecting different reference wavefunctions using only a single set of molecular dynamics trajectories. We conclude that our approach is a further step in making the SC-IVR method a practical tool for first-principles quantum dynamics simulations.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Stephanie Y Y
authors.initials: SY
authors.lastname: Wong
authors.forename: David M
authors.initials: DM
authors.lastname: Benoit
authors.forename: Marius
authors.initials: M
authors.lastname: Lewerenz
authors.forename: Alex
authors.initials: A
authors.lastname: Brown
authors.forename: Pierre-Nicholas
authors.initials: PN
authors.lastname: Roy
mesh_terms: D005557:Formaldehyde / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D014732:Vibration
chemical_list: D005557:Formaldehyde